Lathe centering tool



May 26, 1925.

H. FISH LATHE CENTERING TOOL Filed Jamr l0y 1923 l Patented May 26, 1925.

PATENT OFFICE.

HAROLD FISH, OF BRIDGEPORT, CONNECTICUT.

LATHE CENTER-ING Toor..

i. Application filed January l10, 1923..` `*Serial No. 611,883.

To 071 1/71 0m it amy/concern.'

Be it known that l, HAROLD FisH, a citizen of the United States, residing at Bridgeport, in the county of Fairfield and State of 5 Connecticut, have invented certain new and useful Improvements in .Lathe Centering Tools, of which-the following is a specification.

My invention relates to a new and improved tool and method of making the same.

One of the objects of my invention is to provide a new and improved construction for high speed steel cutting lathe tools and the like. Y

Another object of my invention is to provide a new and improved tool in which the working part, made of high speed steel or stellite or the like, is inserted into a holder made of another material, such as a cheap machine steel.

Another object of my invention is to provide a combination tool in which an operating portion is inserted into a holding portion, and in which the said operating porpletely assembled tool.

Fig. 6 is a view similar to Fig. 5 but is partially in vertical section.

Fig. 7 is a section o1. the line 7-7 of Fig. 6. The holder is made of any suitable material such as a cheap machine steel. As clearly shown'in Fig. 6, this is drilled so as to provide a recess 2 which extends for about half the length thereof. After the drilling ofthe recess 2 has been completed, it is reamed'so as to cause the wall thereof to have a slight taper, namely about 7. The wider part of the said recess 2, after the reaming thereof to bring the desired taper,

is at the frustro-conical tip 3 of the said tion is held very firmly in the said holding 'chilling of the interior wall of theV shank holder- I. ltwill he noted that the inner end 4L of the recess 2 has a conical ctmtour.

A piece of stellite or high speed steel 5 is then taken and a piece of cheap machine steel or thc like is welded to the blunt end thereof. The member 5 is also provided with a conical point 7 which has preferably the same angle as the frustro-conical tip 3 of the holder 1. The combination piece formed by the cutting member 5 and the 65 end member 6 is then turned and ground to exactly the same taper as the holder or recess 2 in the shank 1, so that if the cutting member were driven into the said shank, what is called'a drive fit would be produced and it would be practically impossible to get it out.

I prefer, however, to first put the shan` or holder 1 into a low heat furnace and bring it up to the proper temperature, namely about 800o or 900" F. so as to produce a shrink fit. rlhe cutting member which is cold and has been properly hardened, is powerfully pressed or forced Yinto the correspondingly ta ered hole 2. The hot shank is then quenc ed by any suitable method, so as to cause it to rapidly shrink and a. perfect joint,D or union between the shank and the cutting member is thus produced. 'It Awill be noted that when the 85 tapered cutting member is powerfully forced into the tapered hole 2, that it does not dis-i tort the holder adjacent the conical portion 4 of the hole 2.

I have shown a preferred embodiment of 90 my invention but it is clear that numerous changes and omissions can be madev without departing from its spirit.

When the relatively cold tool iS forced into the hole 2, .which has been enlarged by the 95 heat, the cold walls of the tool are powerfully forced against the hotter interior walls of the shank which are at about 800d F. as before mentioned. -This causes an immediate tube which is followed by the rapid chilling of the entire body of they shank when the quenching operation is performed.

The ordinary machine steel-previously mentioned herein is a carbon steel. It is important to heat the shank or holder '1, made of this carbon steel to a temperature of between 800 to 900 F. because if a lower temperature -is employed then the correet shrink iS not secured when the hot shank is quenched in water, and ifa higher temperature is employed then when'the cutting member is powerfully pressed therein, the shank or body is distorted thus making it useless. Y

1. -A method of making a tool consisting of an operating member having a tapered rear end held in a shank having a correspondingly tapered recess, which consists in heating the shank, then forcing the tapered end of the opera-ting member into the recess of the heated Shank with strong longitudinal pressure, and then cooling the shank, the said longitudinal pressure being sufiicient and the vsaid temperature being such that the operating member is held in theshank Without any relative movement between them.

2. A method of making a cutting tool hole a correspondingly tapered cutting lnein- I any distortion of the parts when said cutting member is forced into said shank.

3. A tool comprising a metal shank having a tapered recess therein having an inclined wall, and an operating member having a correspondingly tapered end fitting in sald recess, the said shank having the metal Wall of said recess being in tight contact with said tapered end and being compressed in a direction perpendicular to said wall, the said shank being shrunk about said tapered end, the said tapered end being in such tight contact with the Wall of said recess to prevent any relative movement.

In testimony whereof I hereunto aiix my signature.

HAROLD insa.4 

